Electrostatically and/or magnetically attractable toner powder

Abstract

Dry toner particles are provided wherein the toner resin includes a mixture of two polymer A and B, A and B being chosen such that an extruded slab with thickness 250 μm of a 50:50 mixture of both has a transmission density (D M ) being between 0.10 and 1.00 higher than the sum of half the transmission density of a 250 μm extruded slab of polymer A alone (D A ) and half the transmission density of a 250 μm extruded slab of polymer B alone (D B ). The polymers A and B are mixed in a weight ratio between 5:1 to 1:5 and make up at least 25% by weight of the total toner resin. The polymer A is a polyester and the polymer B is a polyester or a specified styrene-acrylic copolymer.

What is claimed is:  
     
       1. Dry toner particles comprising a toner resin, wherein: 
       (i) said toner resin includes a mixture of two polymers A and B, said polymers A and B being chosen such that substantially no phase separation occurs in said mixture when in a molten state, resulting in a transmission density (D m ) for an extruded slab of a 50:50 mixture of both polymer A and polymer B with thickness 250 μm being between 0.3 and 0.7 higher than the sum of half the transmission density of a 250 μm extruded slab of polymer A alone (D A ) and half the transmission density of a 250 μm extruded slab of polymer B alone (D B ),  
       (ii) said polymer A being a polyester and said polymer B being a polyester having a carbonyloxy group content of at least 7.5 mol/kg,  
       (iii) said polymer A and B, included in said toner resin, are mixed in a weight ratio 5:1 to  
       (iv) said mixture of said two polymers A and B makes up at least 25% by weight of said toner resin.  
     
     
       2. Dry toner particles according to  claim 1 , wherein said mixture of said two polymers A and B makes up at least 75% by weight of said toner resin. 
     
     
       3. Dry toner particles according to  claim 1 , wherein said toner resin consists of a mixture of said two polymers A and B. 
     
     
       4. Dry toner particles according to  claim 1 , wherein said polymers A and B are mixed in a weight ratio 3:1 to 1:3. 
     
     
       5. Dry toner particles according to  claim 1 , wherein said polymers A and B are mixed in a 50:50 ratio by weight. 
     
     
       6. Dry toner particles according to  claim 1 , wherein both said polymers A and B have a melt viscosity equal to or lower than 10,000 poise (1000 Pas). 
     
     
       7. Dry toner powder according to  claim 1 , wherein said mixture of said two polymers (A and B) consists of a thermoplastic resin (polymer A) combined with a polymer (polymer B) having a more polar character than said polymer A. 
     
     
       8. Dry toner particles according to  claim 7 , wherein said polymer A is a polyester with a carbonyloxy group content lower than 5.5 mol/kg. 
     
     
       9. Dry toner particles according to  claim 8 , wherein said polymer A is a polyester derived from an aliphatic dicarboxylic acid and an alkoxylated 2,2-bis(4-hydroxyphenyl)-propane, and said polymer B is a polyester derived from an aromatic dicarboxylic acid and a diol. 
     
     
       10. Dry toner particles according to  claim 9 , wherein said diol is ethylene glycol optionally mixed with alkoxylated 2,2-bis(4-hydroxyphenyl)-propane, as long as the ethylene glycol content of the totality of diols is more than 50 mol %. 
     
     
       11. Dry toner particles according to  claim 8 , wherein said polymer A is a polyester derived from fumaric acid and dipropoxylated 2,2-bis(4-hydroxyphenyl)-propane. 
     
     
       12. Dry toner particles according to  claim 11 , wherein said polymer B is an aromatic polyester resin derived from terephthalic acid (40 mol %), and isophthalic acid (60 mol %) as aromatic di-acids and a mixture of di-ethoxylated 2,2-bis(4-hydroxphenyl)-propane (40 mol %) and ethylene glycol (60 mol %) as diols. 
     
     
       13. Dry toner particles comprising a toner resin, wherein: 
       (i) said toner resin includes a mixture of two polymers A and B, said polymers A and B being chosen such that an extruded slab with thickness 250 μm of a 50:50 mixture of both has a transmission density (D M ) being between 0.1 and 1.00 higher than the sum of half the transmission density of a 250 μm extruded slab of polymer A alone (D A ) and half the transmission density of a 250 μm extruded slab of polymer B alone (D B ),  
       (ii) said polymer A being a polyester and said polymer B being a polyester,  
       (iii) said polymers A and B, included in said toner resin, are mixed in a weight ration 5:1 to 1:5 and  
       (iv) said mixture of said two polymers A and B makes up at least 25% by weight of said toner resin,  
       wherein said polymer A is a polyester derived from fumaric acid and di-propoxylated 2,2-bis(4-hydroxyphenyl)-propane, and  
       wherein said polymer B is an aromatic polyester resin derived from terephthalic acid (40 mol %), and isophthalic acid (60 mol %) as aromatic di-acids and a mixture of di-ethoxylated 2,2-bis(4-hydroxyphenyl)-propane (40 mol %) and ethylene glycol (60 mol %) as diols.